Final drive decoupling and parking brake arrangement for hydrostatic loader

ABSTRACT

A hydrostatic loader final drive wherein a hydraulic motor transmits power through a quill shaft to reduction gearing coupled to a track driving sprocket wherein means are provided to conveniently disconnect the quill shaft from the reduction gearing or the motor in situations where it is necessary to tow the vehicle with the motor inoperable, and parking and/or emergency brake means are associated with the input side of the reduction gearing to lock same when the motor is inoperable.

United States Patent [1 1 Blom strom et a].

[ Apr. 2, 1974 [54] FINAL DRIVE DECOUPLING AND PARKING BRAKE ARRANGEMENTFOR IIYDROSTATIC LOADER [75] Inventors: Gary D. Blomstrom, Sugar Grove;

Carl T. Butler, Aurora; James M. Kostas, Peoria; Czeslaw J. May, Aurora;Robert D. Nesbit, Morton; Stamos I. Papasideris, Bristol, all of [73]Assignee: Caterpillar Tractor Co., Peoria, Ill.

22 Filed: Dec. 23, 1971 [21] Appl. No.: 211,368

[52] US. Cl. l80/9.62, 180/66 R, 180/70 R, 192/67 R, 192/89 A [51] Int.Cl Bk 17/10 [58] Field of Search.... 180/44 M, 44 F, 44 E, 43 B, 180/66F, F, 72, 71, R, 9.2, 9.62; 192/89 A, 67 R, 93 A, 97, 94

[56] References Cited UNITED STATES PATENTS 3,272,276 9/1966 Budzich /44M 1,370,378 3/1921 Starr 180/43 B 3,439,766 4/1969 Dence et a1. 180/66 F2,439,941 3/1948 Lounsbury 192/89 A X 3,246,715 4/1966 P001 et al 180/44M 3,422,917 l/l969 Guinot 180/44 F 3,027,960 4/1962 Ditel 180/44 F3,480,099 11/1969 Nighswonger et a1 180/44 M 1,783,780 12/1930 Evans180/43 B 2,780,333 2/1957 Reiser et a1. 192/67 R 3,331,482 7/1967Keramas 192/97 Primary Examinerl(enneth H. Betts AssistantExaminer-David M. Mitchell Attorney, Agent, or Firm-Fryer, Tjensvold,Phillips & Lempio [57] ABSTRACT A hydrostatic loader final drive whereina hydraulic motor transmits power through a quill shaft to reductiongearing coupled to a track driving sprocket wherein means are providedto conveniently disconnect the quill shaft from the reduction gearing orthe motor in situations where it is necessary to tow the vehicle withthe motor inoperable, and parking and/or emergency brake means areassociated with the input side of the reduction gearing to lock samewhen the motor is inoperable.

24 Claims, 5 Drawing Figures PATENTEDAPR 2 m4 3,800,901

sum 1 0F 3 INVENTORS GARY D. BLOMSTROM CARL T. BUTLER JAMES M. KOSTASCZESLAW J. MAY ROBERT D. NESBITT STAMOS l. PAPASIDERIS ATTORNEYSPAIENTED R 2 m4 3.800.901

SHEEI 2 0F 3 INVENTORS GARY D. BLOMSTROM CARL T. BUTLER .JAMES M. KOSTASCZESLAW J. MAY ROBERT D. NESBITT STAMOS I. PAPASIDERIS @ZWg 0,4,4, aw

ATTORNEYS PAIENTEDAPR 21974 3.800.901

sum 3 m3 INVENTORS GARY D7 BLOMSTROM CARL T BUTLER JAMES M. KOSTASCZESLAW J. MAY RORERT D. NESBITT STAMOS I. PAPASIDERIS AT TORNEYS FINALDRIVE DECOUPLING AND PARKING BRAKE ARRANGEMENT FOR I-IYDROSTATIC LOADERBACKGROUND OF THE INVENTION Hydrostatic drives are variously employedfor the transmission of power in numerous mechanisms such as winches,scraper elevators, and loaders. For example, in a hydrostatic driveloader, each track is driven by a separate motor coupled by reductiongearing to a track driving sprocket. Steering, braking, and vehiclespeed is achieved through the hydraulic pumps and drive motors whichreplace the conventional transmission, brakes, and steering clutches.

One of the problems encountered with hydrostatic drive vehicles is thatshould it become necessary to tow the vehicle, there are no clutches ortransmissions with which the drive to the tracks can be decoupled.Towing the vehicle with the hydraulic motor coupled to the final drivewould result in severe damage to the motor and/or pump.

Another problem encountered with hydrostatic drive vehicles is thatsince the primary braking of the vehicle is accomplished with thehydraulic motors, other means must be provided for emergency and/orparking brakes. It is of course desirable that such brake means beprovided in as small a package as possible. Similar problems to thoseposed above with respect to hydrostatic drive loaders and other vehiclesare encountered with the hydrostatic drives of other mechanisms withregard to the decoupling of the hydraulic motor and emergency braking ofthe drive.

SUMMARY OF THE INVENTION The general object of the present invention isto provide a hydrostatic final drive for a loader, or the like,characterized by a simple conveniently disconnectable mechanism forcoupling the hydraulic motor to the reduction gearing of the drive, andcompact low torque parking and/or emergency braking means operablyassociated with the input side of the gear drive.

In the accomplishment ofthe foregoing and other objects and advantagesof the invention there is generally provided a hydrostatic driveincluding a double reduction gear train, preferably provided withplanetary gearing at the output side thereof, coupling a hydraulic motorat the input side of the train to a rotary drive member at the outputside, such as a track driving sprocket of a loader. The motor is coupledto an input gear of the first reduction unit of the train by means of aquill shaft spline connected at its opposite ends to the motor and gear.

In accordance with a particularly important aspect of the invention,means are provided for manually translating the quill shaft to disengagethe spline connection at one of its ends, thereby decoupling the motorfrom the gear drive. In one embodiment of the disconnect means a jackbolt threaded through a tapped bore of a housing enclosing the geartrain is rotatably coaxially secured to the end of the quill shaftadjacent the input gear to normally retain the shaft in engaged positionwith the motor and gear. Unscrewing of the bolt translates the shaft todisengage the splined connection between the shaft and input gear.

In another embodiment of the disconnect means, the quill shaft is springloaded into normally engaged posi tion with the motor and gear, and amanually rotatable cam engaging the end of the shaft adjacent the gearmay be rotated to translate the shaft against the loading of the springand thereby disengage the splined connection between the shaft and gear.

In accordance with another particularly important aspect of theinvention, brake means are coupled to the input reduction unit of thetrain for selectively locking same against rotation, the braking forcerequired being relatively low and thus the brake package relativelysmall, since the greater multiplication of torque occurs in the outputplanetary reduction unit. In one embodiment, the brake means arecoaxially disposed about the disconnectable quill shaft to selectivelyapply braking torque to the input gear of the input reduction unit. Inanother embodiment, the brake means are coupled to the output gear ofthe input reduction unit to selectively apply braking torque thereto. Ineither case, locking of the input reduction unit locks the entire geartrain and thus the output track driving sprocket. The brake means arearranged to be selectively releasable or disconnectable from the inputreduction unit to free the tram for free wheeling movement.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a fragmentary sideelevational view depicting a portion of the track driving means of ahydrostatic drive loader embodying drive decoupling and braking means inaccordance with the present invention.

FIG. 2 is a view similar to FIG. 1, but depicting a modified form of theinvention.

FIG. 3 is a sectional view taken at line 3-3 of FIG. 1.

FIG. 4 is a sectional view taken at line 4-4 of FIG. 3.

FIG. 5 is a sectional view taken at line 5-5 of FIG. 2.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION Referringnow to the drawings in detail, particularly FIGS. 1 and 3, the inventionwill be seen to be illustrated with respect to a substantiallyconventional hydrostatic track driving means of a track-type loaderwhich includes a track driving sprocket 11 adapted to be driven by ahydraulically powered double reduction final drive assembly 12.

Basically, the drive assembly includes a housing 13 rigidly secured to amain frame partially shown at 14. Driving power is directed from ahydraulic motor 16, secured to frame 14, through a quill shaft 17 to apinion 18 coupled thereto and rotatably mounted within bearings 19 fordriving engagement with a larger gear 21, the pinion l8 and gear 21comprising the input and output gears of a first or input reduction unitof a gear drive train. Gear 21 is suitably rotatably mounted withinhousing 13 by means of bearings 22 and nonrotatably secured to a driveshaft 23 having its opposite end formed as a sun gear 24.

The sun gear 24 is part of a planetary gear drive which comprises thesecond or output reduction unit of the drive train. More particularly,the sun gear meshingly engages a plurality of circumferentially spacedplanet gears 26 carried by pins 27 supported by a planet carrier member28. Each of the planet gears also meshes with an internal ring gear 29secured to a stationary member 3! splined to a spindle 32 which is anintegral part of housing 13. The ring gear 29 is secured to member 31 byplates 33 which are bolted thereto and extend into notches 34 in thering gear. Both the sun gear and ring gear are mounted for radial float.

The carrier member 28 has its peripheral edges rigidly secured to theouter end of a hollow hub 36 having at its inner end a radiallyoutwardly projecting flange 37 to which the sprocket 11 is secured.Thus, when the sun gear 24 is driven by rotation of shaft 23, it causesthe planet gears 26 to walk around within the fixed ring gear 29 andthereby rotate the sprocket hub 36 to which the carrier member issecured, at a lesser velocity than the shaft 23.

An annular ring 35 is disposed between member 31 and spindle 32 toprovide means to transmit the loads imposed on the hub 36 to the spindlethrough bearings 38 and 39. A removable cover plate 41 bridging thecentral opening of the carrier member 28 is provided to facilitateinspection or servicing of the final drive gearing. Suitable seals 42are provided to prevent entry of dirt and water.

With the hydrostatic drive assembly 12 outlined hereinbefore, it will beappreciated that there are no clutches or transmissions with which thegear drive train between the hydraulic motor 16 and sprocket 11 can bedecoupled to prevent damage to the motor in situations where the vehiclemust be towed with the motor inoperable. However, this difficulty isovercome in accordance with the present invention by the provision of adisconnectable mechanism coupling the hydraulic motor 16 to the inputgear 18 of the reduction gear train.

As previously noted quill shaft 17 directs power from motor 16 to theinput pinion gear 18. In this regard, the gear 18 is of elongated hollowcylindrical configuration and the quill shaft is coaxially disposedtherein. One end of the quill shaft is spline connected to the motor asindicated at 43, and the opposite end of the shaft is spline connectedto the gear as indicated at 44. In accordance with the broader aspectsof the disconnectable mechanism of the present invention, means areprovided to manually longitudinally translate the quill shaft todisengage the spline connection 44.

More particularly, in the embodiment depicted in FIGS. 3 and 4, a spring46 is coaxially disposed about shaft 17 and acts between a retainingring 47 projecting radially inward from the bore wall of the gear and aretaining ring 48 projecting radially outward from the shaft adjacentspline connection 44 to thereby resiliently urge the shaft into a normalcoupled position.

Disengagement of the spline connection is then accomplished by means ofa cam 49 which is rotatable into engagement with an end tip portion 51of the shaft projecting from the distal end of the gear bore withrespect to the motor. In this regard cam rotation in thecounterclockwise direction, as viewed in FIG. 3, forces the shaftleftward against the force of spring 46 to disengage the splineconnection 44, and in an over-center position holds the shaft in thedisengaged position.

The cam 49 is keyed to a transverse shaft 52 which extends exteriorlythrough the side of the housing 13 and is provided with a hex head 53 atits exterior end at a location where it can be readily turned with awrench. A compression spring 54 coaxially disposed about shaft 52 andacting between the cam and interior of the housing serves to resilientlyrestrain shaft rotation. Thus, when the shaft 52 is turned by means of awrench engaging the hex head 53 the cam is rotated to translate thequill shaft 17 to a disengaged position, thus allowing the final driveto be free-wheeling when the vehicle is towed and preventing damage tothe hydraulic motor.

To re-engage the spline connection 44, the cam is rotated clockwise tothe original position and the spring 46 forces the quill shaft 17rightwardly. If the splines are misaligned, the hydraulic motor 16 canbe rotated slightly, by manipulating the machine controls, and thespring will shift the quill shaft to the engaged position when alignmentof the spline connections is achieved.

Considering now an alternative form of disconnectable mechanism inaccordance with the present invention for decoupling the hydraulic motor16 from the input gear 18 of the drive train, reference is made to FIG.5. As shown therein, the end of quill shaft 17 adjacent splineconnection 44 is rotatably coaxially secured to a jack bolt 56 threadedthrough a tapped bore 57 in a front wall of housing 13 inwardly spacedfrom sprocket hub 36. More particularly, the tip end of the bolt isrotatably received in a coaxial cylindrical recess 58 formed in the endface of the quill shaft. The tip end of the bolt is provided with acircumferential groove 59 which is freely traversed by a transverse pin61 secured across the recess wall to restrain longitudinal translationof the bolt relative to the shaft while permitting rotationtherebetween. The exterior end of the bolt is provided with a hex head62 which may be engaged with a wrench to facilitate unscrewing of thebolt. Unscrewing of the bolt effects rightward translation of the quillshaft (as viewed in FIG. 5) to thereby disengage the spline connection44 between the shaft and input gear 18.

Since primary braking in a hydrostatic drive system of the typedescribed hereinbefore is accomplished with the hydraulic drive motors,other means must be provided for parking and/or emergency brakes. It isdesirable that the required braking torque be as small as possible inorder that the brake means may be made compact. Thus in accordance withthe present invention brake means are coupled to the input reductionunit of the gear drive train to selectively lock the entire trainagainst rotation. In this regard, since the greater multiplication oftorque occurs in the output planetary reduction unit, the braking torquerequired to stop the input reduction unit is relatively low.

As shown in FIG. 3, the brake means may advantageously comprise a springapplied hydraulically released parking brake 63 disposed within a brakehousing 64 coaxially disposed about the quill shaft 17 and coaxial inputgear 18 to selectively apply braking torque to the latter. The brakehousing 64 is secured to the housing 13 by bolts 65. The brake includesa first set of friction-faced disks 66 coaxially secured to the inputgear 18 to rotate therewith and a second set of coaxial contact disks 67interleaved with disks 66 and which have their outer peripheries notchedto register with bolts 65 to prevent rotation of disks 67. The disks 66and disks 67 are both free to move axially. A pressure plate 68 disposedadjacent to one of the frictionfaced disks 66 is secured to longitudinalguide rods 69 which slidably traverse bores extending through an endwall 70 of the brake housing.

A plurality of compression springs 71 are provided to act longitudinallybetween end wall 70 and pressure plate 68 thereby normally urging disks66 into frictional engagement with disks 67 and applying braking torqueto the gear 18. The guide rods 69 are secured to an end plate 72disposed exteriorly of end wall 70. The end wall 70 is formed with aplurality of chambers 73, each of which faces a flexible diaphragm 74which in turn has a piston 75 secured thereto in abutting engagementwith the end plate 72. The chambers 73 are communicated by conduit means(not shown) with the hydraulic system of the vehicle such that undernormal running conditions hydraulic pressure is supplied to thechambers. The pressure acts upon diaphragms 74 to flex same, moving thepiston 75 outwardly and thereby urge the end plate 72 and plate 68secured thereto against the loading force of springs 71. As a result,the brake is released when the vehicle is operated under normal runningconditions. In the event of shut down or failure of the hydraulicsystem, hydraulic pressure in chambers 73 is terminated whereupon thesprings 71 effect application of the brake to thereby lock the inputgear 18, and therefore the entire gear drive train to the sprocket 11.

In the event it is necessary to tow the vehicle and the gear train hasbeen decoupled from the hydraulic motor 16 in the manner previouslydescribed, it is of course necessary to release the brake 63 in order tofree the drive for free running operation. Such release of the brake maybe advantageously effected by means of a hand pump and associatedvalving (not shown) which are accessible to the operator andcommunicably coupled to chambers 73. Manipulation of the hand pumpapplies hydraulic pressure to the chambers to release the brake undersuch circumstances.

An alternative form of brake means is shown in FIG. 5 which is generallysimilar to that described above except in its point of application tothe gear drive train. More particularly, in the alternative design aspring applied hydraulically released parking brake 76 is mounted uponframe 14 and coupled by means of a shaft 77 to a pinion gear 78 whichmeshes with the output gear 21 of the input reduction unit of the drivetrain. The brake 76 is similar in construction to brake 63 and thereforenot described in detail herein, it sufficing to state that brake 76 isarranged to act upon shaft 77 in the same manner as brake 63 acts upongear 18.

Brake 76 is hydraulically released responsive to the pressure existingin the hydraulic system of the vehicle under normal running conditionsthereof. Shaft 77 and gear 78 are thus freed for rotation with gear 21such that the entire gear train is in an unlocked condition. Upon shutdown or failure of the hydraulic system spring applied braking torque isexerted on shaft 77 and gear 78. The braked gear 78 thus locks gear 21,and therefore the entire drive train.

It will be appreciated that with the brake 76, there still exists theproblem of releasing or decoupling of the brake to permit towing of thevehicle. Such release of the brake may be effected by means ofa handpump as in the case of brake 63. However, brake decoupling may beaccomplished in a simplified manner by providing shaft 77 as a quillshaft coupled to gear 78 by means of a spline connection 79, andproviding means for manually longitudinally translating the quill shaftto disengage such spline connection in the same manner as employed withquill shaft 17 to decouple motor 16 from input gear 18. In this regard,the end of quill shaft 77 adjacent spline connection 79 may be rotatablycoaxially secured to a jack bolt 81 threaded through a tapped bore 82 ina front wall of housing 13, in the same manner as jack bolt 56associated with quill shaft 17. The exterior end of the bolt is providedwith a hex head 83 which may be engaged with a wrench to facilitateunscrewing of the bolt. Unscrewing of the bolt effects rightwardtranslation of quill shaft 77 to thereby disengage the spline connection79 between the shaft and gear 78. The entire gear drive train is thusdecoupled from brake 76 to permit towing of the vehicle. It will beappreciated that in place of the jack bolt 81, a cam arrangement of thevariety previously described with respect to the embodiment of FIGS. 3and 4 may be employed to effect disengaging translation of the quillshaft 77.

Although the invention has been hereinbefore described and illustratedin the accompanying drawings with respect to several preferredembodiments, it will be appreciated that various changes andmodifications may be made therein without departing from the true spiritand scope of the invention, and thus it is not intended to limit theinvention except by the terms of the appended claims.

What is claimed is:

1. In a hydrostatic drive including a reduction gear train having aninput reduction unit with an internally splined input gear, andhydraulic motor means for coupling to said internally splined input gearin driving relationship thereto, said hydraulic motor means having aninternally splined output connection member, the combination comprisinga quill shaft having a circular cross sectional configuration with ahollow axially extending interior portion and having first and secondexternally disposed axially spaced-apart splines at opposite endsthereof and said quill shaft being spline connected at said oppositeends to respectively said internally splined motor output connectionmember and said internally splined input gear, said quill shaft beinglongitudinally translatable between a first position wherein said secondspline is engaged with said internally splined input gear and a secondposition wherein at least one of said first and second splines isdisengaged from one of said internally splined output connection memberor said internally splined input gear, means for physically translatingsaid quill shaft between said first and second positions, saidinternally splined input gear also having externally disposed brakeconnection means, and brake means for directly applying braking force tosaid externally disposed connection means and to said input reductionunit to lock said input reduction unit against rotation.

2. The combination of claim 1, further defined by means longitudinallyspring loading said quill shaft into said first position, and meansincluding a rotatable cam directly engaging an end of said quill shaftfor urging same against the spring loading force into said secondposition upon rotation of said cam.

3. The combination of claim 2, further defined by a shaft secured tosaid cam for rotating same extending through a wall of a housingenclosing said gear train, said shaft having a head at its external endfor rotation by a tool.

4. The combination of claim 1, further defined by a jack bolt threadedthrough a wall of a housing enclosing said gear train, said jack boltrotatably coaxially secured to an end of said quill shaft to normallylongitudinally retain same in said first position, said jack boltlongitudinally translating said quill shaft to said second positionresponsive to unscrewing of said jack bolt.

5. The combination of claim 4, further defined by said end of said quillshaft having a recess rotatably receiving the tip end of said jack bolt,said tip end of said bolt jack having a circumferential groove, and atransverse pin secured across the wall of said recess and freelytraversing said groove.

6. The combination of claim 1, further defined by said brake meanscomprising a spring applied hydraulically released brake.

7. The combination of claim 6, further defined by said brake beingcoupled to an output gear of said input reduction unit to selectivelyapply braking torque thereto.

8. The combination of claim 1, further defined by said brake comprisinga first plurality of disks coaxially secured to said internally splinedinput gear, a second plurality of disks coaxially disposed with respectto said internally splined input gear and interleaved with said firstplurality of disks, a brake housing enclosing said disks, loadingsprings acting between said brake housing and said second plurality ofdisks-to normally resiliently urge same into frictional engagement withsaid first plurality of disks, and hydraulically actuated means carriedby said brake housing and coupled to said second plurality of disks tourge same against the force of said springs to disengage said secondplurality of disks from said first plurality of disks responsive tohydraulic pressure.

9. The combination of claim 7, further defined by a braking gear meshedwith said output gear, and a second shaft coupled to said braking gear,said brake coupled to said second shaft to selectively apply brakingtorque thereto.

10. The combination of claim 9, further defined by said second shaftbeing a quill shaft spline connected to said braking gear, said secondshaft being longitudinally translatable between a first position whereinthe spline connection thereof is engaged and a second position whereinthe spline connection thereof is disengaged, and means for manuallylongitudinally translating said second shaft between said first andsecond positions thereof.

11. The hydrostatic drive of claim 1 in a loader and further comprisinga planetary output reduction unit in driving relation to a track drivingsprocket, and a spring applied hydraulically released brake meanscoupled to said input reduction unit for selectively applying brakingtorque thereto.

12. The invention of claim 13, further defined by means longitudinallyspring loaded said quill shaft into said first position, a rotatable camengaging an end of said quill shaft for urging same against the springloading force upon cam rotation, said cam being rotatable between afirst position wherein said shaft is in said first position thereof anda second position wherein said cam holds said shaft in said secondposition thereof, and a second shaft secured to said cam to impartrotation thereto, said second shaft extending through a wall of ahousing enclosing said gear train and having a head at its external endfor engagement by a wrench.

13. The invention of claim 13, further defined by a jack bolt threadedthrough a wall of a housing enclosing said gear train, said boltrotatably coaxially secured to an end of said shaft to normallylongitudinally retain same in said first position, said boltlongitudinally translating said shaft to said second position responsiveto unscrewing of said bolt.

14. The invention of claim 13, further defined by said brake comprisinga first plurality of disks coaxially secured to said input gear, asecond plurality of disks co axially disposed with respect to said inputgear and interleaved with said first plurality of disks, a brake housingenclosing said disks, loading springs acting between said brake housingand said second plurality of disks to normally resiliently urge sameinto frictional engagement with said first plurality of disks, andhydraulically actuated means carried by said brake housing and coupledto said second plurality of disks to urge same against the force of saidsprings to disengage said second plurality of disks from said firstplurality of disks responsive to hydraulic pressure.

15. The invention of claim 14, further defined by means longitudinallyspring loading said quill shaft into said first position, a rotatablecam engaging an end of said shaft for urging same against the springloading force upon cam rotation, said cam being rotatable between afirst position wherein said shaft is in said first position thereof anda second position wherein said cam holds said shaft in said secondposition thereof, and a second shaft secured to said cam to impartrotation thereto, said second shaft extending through a wall of ahousing enclosing said gear train and having a head at its external endfor engagement by a wrench.

16. The invention of claim 14, further defined by a jack bolt threadedthrough a wall of a housing enclosing said gear train, said boltrotatably coaxially secured to an end of said quill shaft to normallylongitudinally retain same in said first position, said boltlongitudinally translating said shaft to said second position responsiveto unscrewing of said bolt.

17. The invention of claim 11, further defined by said braking meansacting upon said input reduction unit second shaft coupled to saidbraking means, said braking means coupled to said second shaft toselectively apply braking torque thereto.

18. The invention of claim 17, further defined by means longitudinallyspring loading said quill shaft into said first position thereof, arotatable cam engaging an end of said first shaft for urging sameagainst the spring loading force upon cam rotation, said cam rotatablebetween a first position wherein said quill shaft is in said firstposition thereof and a second position wherein said cam holds said quillshaft in said second position thereof, and a third shaft secured to saidcam to impart rotation thereto, said third shaft extending through awall of a housing enclosing said gear train and having a head at itsexternal end for engagement by a wrench.

19. The invention of claim 17, further defined by a jack bolt threadedthrough a wall of a housing enclosing said gear train, said boltrotatably coaxially secured to an end of said quill shaft to normallylongitudinally retain same in said first position, said boltlongitudinally translating said first shaft to said second positionthereof responsive to unscrewing of said bolt.

20. The invention of claim 17, further defined by said second shaftbeing a quill shaft spline connected to said braking means, said secondshaft being longitudinally translatable between a first position whereinthe spline connection thereof is engaged and a second position whereinthe spline connection thereof is disengaged, and means for manuallylongitudinally translating said second shaft between said first andsecond positions thereof.

21. The invention of claim 20, further defined by means longitudinallyspring loading said quill shaft into said first position thereof, arotatable cam engaging an end of said quill shaft for urging sameagainst the spring loading force upon cam rotation, said cam rotatablebetween a first position wherein said quill shaft is in said firstposition thereof and a second position wherein said cam holds said quillshaft in said second position thereof, and a third shaft secured to saidcam to impart rotation thereto, said third shaft extending through awall of a housing enclosing said gear train and having a head at itsexternal end for engagement by a wrench.

22. The invention of claim 21, further defined by a jack bolt threadedthrough a wall of said housing enclosing said gear train, said jack boltrotatably coaxially secured to an end of said second shaft to normallylongitudinally retain same in said first position thereof,

said second bolt longitudinally translating said second shaft to saidsecond position thereof responsive to unscrewing of said second bolt.

23. The invention of claim 20, further defined by a 5 jack bolt threadedthrough a wall of a housing enclosing said gear train, said boltrotatably coaxially secured to an end of said quill shaft to normallylongitudinally retain same in said first position, said boltlongitudinally translating said quill shaft to said second positionthereof responsive to unscrewing of said bolt.

24. The invention of claim 23, further defined by a second jack boltthreaded through a wall of said housing enclosing said gear train, saidsecond bolt rotatably coaxially secured to an end of said second shaftto normally longitudinally retain same in said first position thereof,said second bolt longitudinally translating said second shaft to saidsecond position thereof responsive to unscrewing of said second bolt.

1. In a hydrostatic drive including a reduction gear train having aninput reduction unit with an internally splined input gear, andhydraulic motor means for coupling to said internally splined input gearin driving relationship thereto, said hydraulic motor means having aninternally splined output cOnnection member, the combination comprisinga quill shaft having a circular cross sectional configuration with ahollow axially extending interior portion and having first and secondexternally disposed axially spaced-apart splines at opposite endsthereof and said quill shaft being spline connected at said oppositeends to respectively said internally splined motor output connectionmember and said internally splined input gear, said quill shaft beinglongitudinally translatable between a first position wherein said secondspline is engaged with said internally splined input gear and a secondposition wherein at least one of said first and second splines isdisengaged from one of said internally splined output connection memberor said internally splined input gear, means for physically translatingsaid quill shaft between said first and second positions, saidinternally splined input gear also having externally disposed brakeconnection means, and brake means for directly applying braking force tosaid externally disposed connection means and to said input reductionunit to lock said input reduction unit against rotation.
 2. Thecombination of claim 1, further defined by means longitudinally springloading said quill shaft into said first position, and means including arotatable cam directly engaging an end of said quill shaft for urgingsame against the spring loading force into said second position uponrotation of said cam.
 3. The combination of claim 2, further defined bya shaft secured to said cam for rotating same extending through a wallof a housing enclosing said gear train, said shaft having a head at itsexternal end for rotation by a tool.
 4. The combination of claim 1,further defined by a jack bolt threaded through a wall of a housingenclosing said gear train, said jack bolt rotatably coaxially secured toan end of said quill shaft to normally longitudinally retain same insaid first position, said jack bolt longitudinally translating saidquill shaft to said second position responsive to unscrewing of saidjack bolt.
 5. The combination of claim 4, further defined by said end ofsaid quill shaft having a recess rotatably receiving the tip end of saidjack bolt, said tip end of said bolt jack having a circumferentialgroove, and a transverse pin secured across the wall of said recess andfreely traversing said groove.
 6. The combination of claim 1, furtherdefined by said brake means comprising a spring applied hydraulicallyreleased brake.
 7. The combination of claim 6, further defined by saidbrake being coupled to an output gear of said input reduction unit toselectively apply braking torque thereto.
 8. The combination of claim 1,further defined by said brake comprising a first plurality of diskscoaxially secured to said internally splined input gear, a secondplurality of disks coaxially disposed with respect to said internallysplined input gear and interleaved with said first plurality of disks, abrake housing enclosing said disks, loading springs acting between saidbrake housing and said second plurality of disks to normally resilientlyurge same into frictional engagement with said first plurality of disks,and hydraulically actuated means carried by said brake housing andcoupled to said second plurality of disks to urge same against the forceof said springs to disengage said second plurality of disks from saidfirst plurality of disks responsive to hydraulic pressure.
 9. Thecombination of claim 7, further defined by a braking gear meshed withsaid output gear, and a second shaft coupled to said braking gear, saidbrake coupled to said second shaft to selectively apply braking torquethereto.
 10. The combination of claim 9, further defined by said secondshaft being a quill shaft spline connected to said braking gear, saidsecond shaft being longitudinally translatable between a first positionwherein the spline connection thereof is engaged and a second positionwherein the spline connection thereof is disengaged, and mEans formanually longitudinally translating said second shaft between said firstand second positions thereof.
 11. The hydrostatic drive of claim 1 in aloader and further comprising a planetary output reduction unit indriving relation to a track driving sprocket, and a spring appliedhydraulically released brake means coupled to said input reduction unitfor selectively applying braking torque thereto.
 12. The invention ofclaim 13, further defined by means longitudinally spring loaded saidquill shaft into said first position, a rotatable cam engaging an end ofsaid quill shaft for urging same against the spring loading force uponcam rotation, said cam being rotatable between a first position whereinsaid shaft is in said first position thereof and a second positionwherein said cam holds said shaft in said second position thereof, and asecond shaft secured to said cam to impart rotation thereto, said secondshaft extending through a wall of a housing enclosing said gear trainand having a head at its external end for engagement by a wrench. 13.The invention of claim 13, further defined by a jack bolt threadedthrough a wall of a housing enclosing said gear train, said boltrotatably coaxially secured to an end of said shaft to normallylongitudinally retain same in said first position, said boltlongitudinally translating said shaft to said second position responsiveto unscrewing of said bolt.
 14. The invention of claim 13, furtherdefined by said brake comprising a first plurality of disks coaxiallysecured to said input gear, a second plurality of disks coaxiallydisposed with respect to said input gear and interleaved with said firstplurality of disks, a brake housing enclosing said disks, loadingsprings acting between said brake housing and said second plurality ofdisks to normally resiliently urge same into frictional engagement withsaid first plurality of disks, and hydraulically actuated means carriedby said brake housing and coupled to said second plurality of disks tourge same against the force of said springs to disengage said secondplurality of disks from said first plurality of disks responsive tohydraulic pressure.
 15. The invention of claim 14, further defined bymeans longitudinally spring loading said quill shaft into said firstposition, a rotatable cam engaging an end of said shaft for urging sameagainst the spring loading force upon cam rotation, said cam beingrotatable between a first position wherein said shaft is in said firstposition thereof and a second position wherein said cam holds said shaftin said second position thereof, and a second shaft secured to said camto impart rotation thereto, said second shaft extending through a wallof a housing enclosing said gear train and having a head at its externalend for engagement by a wrench.
 16. The invention of claim 14, furtherdefined by a jack bolt threaded through a wall of a housing enclosingsaid gear train, said bolt rotatably coaxially secured to an end of saidquill shaft to normally longitudinally retain same in said firstposition, said bolt longitudinally translating said shaft to said secondposition responsive to unscrewing of said bolt.
 17. The invention ofclaim 11, further defined by said braking means acting upon said inputreduction unit second shaft coupled to said braking means, said brakingmeans coupled to said second shaft to selectively apply braking torquethereto.
 18. The invention of claim 17, further defined by meanslongitudinally spring loading said quill shaft into said first positionthereof, a rotatable cam engaging an end of said first shaft for urgingsame against the spring loading force upon cam rotation, said camrotatable between a first position wherein said quill shaft is in saidfirst position thereof and a second position wherein said cam holds saidquill shaft in said second position thereof, and a third shaft securedto said cam to impart rotation thereto, said third shaft extendingthrough a wall of a housing enclOsing said gear train and having a headat its external end for engagement by a wrench.
 19. The invention ofclaim 17, further defined by a jack bolt threaded through a wall of ahousing enclosing said gear train, said bolt rotatably coaxially securedto an end of said quill shaft to normally longitudinally retain same insaid first position, said bolt longitudinally translating said firstshaft to said second position thereof responsive to unscrewing of saidbolt.
 20. The invention of claim 17, further defined by said secondshaft being a quill shaft spline connected to said braking means, saidsecond shaft being longitudinally translatable between a first positionwherein the spline connection thereof is engaged and a second positionwherein the spline connection thereof is disengaged, and means formanually longitudinally translating said second shaft between said firstand second positions thereof.
 21. The invention of claim 20, furtherdefined by means longitudinally spring loading said quill shaft intosaid first position thereof, a rotatable cam engaging an end of saidquill shaft for urging same against the spring loading force upon camrotation, said cam rotatable between a first position wherein said quillshaft is in said first position thereof and a second position whereinsaid cam holds said quill shaft in said second position thereof, and athird shaft secured to said cam to impart rotation thereto, said thirdshaft extending through a wall of a housing enclosing said gear trainand having a head at its external end for engagement by a wrench. 22.The invention of claim 21, further defined by a jack bolt threadedthrough a wall of said housing enclosing said gear train, said jack boltrotatably coaxially secured to an end of said second shaft to normallylongitudinally retain same in said first position thereof, said secondbolt longitudinally translating said second shaft to said secondposition thereof responsive to unscrewing of said second bolt.
 23. Theinvention of claim 20, further defined by a jack bolt threaded through awall of a housing enclosing said gear train, said bolt rotatablycoaxially secured to an end of said quill shaft to normallylongitudinally retain same in said first position, said boltlongitudinally translating said quill shaft to said second positionthereof responsive to unscrewing of said bolt.
 24. The invention ofclaim 23, further defined by a second jack bolt threaded through a wallof said housing enclosing said gear train, said second bolt rotatablycoaxially secured to an end of said second shaft to normallylongitudinally retain same in said first position thereof, said secondbolt longitudinally translating said second shaft to said secondposition thereof responsive to unscrewing of said second bolt.